It is desirable to generate a synthetic scene for testing and calibrating various image sensors, such as visible, ultraviolet and infrared (IR) imaging devices. There has been progress in developing scene projectors for use in Hardware-in-the-Loop (HWIL) Simulations that are capable of end-to-end testing and calibration of imaging devices, or sensors.
For example, it is common to incorporate seekers into missiles, for guiding the missile onto a target. When a new missile is developed it must be tested to ensure that the design is robust and that it behaves the way it is expected to. Tests are carried out at all stages of development on the components and sub-systems, but a test is needed for the complete, assembled missile, in order to check that the sub-systems work together as intended, and that the missile is capable of doing the job it is required to do. The missile sub-systems can be tested simultaneously in a representative environment by firing the missile against a test target at a missile firing range. This is an essential part of any new missile development program, although it is very expensive and time consuming. A way of significantly reducing the number of missile firings required is to use validated representative performance models. The HWIL testing allows interaction and response of many of the missile sub-systems to be tested repeatedly in a controlled environment, at much lower cost and with much faster timescales than firing trials.
As another example, it is common to incorporate a camera into a turret disposed in the nose of a military aircraft. An end-to-end test of the camera may provide an image simulation system having a scene generator that creates a visible image and projects that image toward the camera. Typically, the scene generator may be a workstation or minicomputer having software necessary to generate the digital scene data, at a rate up to and including real-time rate. Depending on the requirements of the camera, the projected image may consist of a simple geometric pattern, or a rendered perspective of many objects. An environmental simulator may also be added to allow motion of the camera under test, by using predetermined motion of the turret. The motion may include roll and pitch that simulate the camera scanning a target of interest on a ground terrain.
Thus, image generators and projectors are known for end-to-end testing and calibration of image sensors. These generators and projectors, however, are limited for producing collimated, but narrow fields-of-view that provide only partial field coverage or are limited in resolution or available aperture, precluding the simultaneous testing of systems comprising a multiplicity of cameras. This effectively limits testing to a single sensor device, or camera at any one time.
Recently, aircraft payloads have included multiple visible cameras and IR cameras installed as an array in a single turret. These cameras operate simultaneously providing an ultra-wide field scene with many entrance pupils that are designed to view a substantially wide area of interest. For example, field coverage may be at least 50 degrees wide, with some coverage requiring up to 80 degrees of width.
Consequently a need has arisen for an ultra-wide field scene generator and projector for qualifying and calibrating multiple camera imagers having many entrance pupils covering, in cooperative combination, a substantially wide field-of-view. The present invention, as will be explained, addresses that need.